The present invention is directed to winding tubes primarily used in initially collecting and winding newly spun synthetic yarn as it exits a spinneret. More particularly the invention is directed to a reusable winding tube which will withstand winding speeds of up to 30,000 R.P.M. and above and will also accept a removable end cap on at least one end thereof.
In conventional automatic winding operations, yarn is wound onto a cylindrical laminated paper tube (hereinafter referred to as a "paper tube"). In the past, such laminated paper tubes have been subjected to winding operations at speeds of 3500-4000 meters per minute (approximately 12,000-14,000 R.P.M.) Paper tubes will delaminate at speeds in the range of 6000 meters per minute (approximately 18,000-20,000 R.P.M.) As the yarn spinning speeds increase, winding speeds must also increase. As a result laboratory experiments are now being conducted which require winding speeds of 10,000-12,000 meters per minute (approximately 30,000 R.P.M.) Obviously, new yarn tube constructions are required which will resist the loads imposed at such speeds, particularly tensile stress. Such loads ("hoop stress") have been calculated to be as high as 8.O.times.10.sup.4 kilonewtons per square meter. Further, since the winding tubes are intended for use on existing equipment, it is desirable that such new winding tubes maintain the same effective outer diameter and inner diameter, so as to be compatible with existing drive rolls and mounting spindles.
As a further consideration of the present invention and by way of background, one end of such paper tubes includes a peripheral starting groove in the surface thereof adjacent one end (U.S. Pat. No. 3,103,305). The starting groove is often, but not always, divided into two arcuate portions. The greater arcuate portion (approximately 270.degree.) is wider and referred to as the lead-in portion, while the smaller (approximately 90.degree.) arcuate portion (locking portion) is narrower and locks one or more of the initial strands of yarn therein during the initial few turns of the automatic winding operation. Alternatively, when processing fine denier yarns, the starting groove may be a constant cross-section throughout.
The starting groove generally extends completely around the periphery of the yarn carrier, as will be described hereinafter. It is possible, however, that the starting groove extend only partially around the yarn carrier, as long as the arcuate length is sufficient to achieve a reliable latch-up. Therefore, while the ensuing description may be directed to a peripheral starting groove, it should be kept in mind that starting grooves which extend partially around the tube are also envisioned.
These strands are hereinafter and commonly referred to as the "waste bunch." The completed yarn package is removed from the winding machine, and stored or shipped for further processing (e.g., weaving, knitting, or texturizing). The yarn is removed from the yarn carrier during a subsequent operation such as weaving, knitting or texturizing.
When the yarn package is positioned on some type of creel for such further processing, the transfer tail of one package is conventionally severed at or near the waste bunch and tied to the front end of the successive yarn package. After the yarn is removed from the package, the last few strands of the waste bunch remain wedged in the starting groove. Previous attempts to remove the remaining strands have included vacuum stripping, cutting of the strands, or a combination of both. Neither technique is entirely satisfactory. Vacuum stripping simply does not remove all the fibrous or filamentary material. Using a knife to sever the bunch generally results in damage to the surface of the paper tube making it unsuitable for further use. Such damage occurs when the laminates of the paper tube are nicked, cut, or otherwise interrupted. Use of a damaged tube at high speeds then tends to result in delamination.
As a result, conventional paper winding tubes are generally not reusable. There have been some attempts to reuse the tubes at least once by providing a transfer groove at each end of the tube. However, often the paper tube is otherwise damaged during the automatic doffing and emplacement operations which substantially eliminates the reuse of the paper tubes. Conventional paper tubes are relatively expensive (25 to $1.00 apiece) and hundreds of thousands or even millions of tubes are used each year by typical yarn manufacturers. Thus the cost of non-reusable yarn carriers is extremely high and the search for a satisfactory reusable yarn tube has been underway for some time.
Merely the replacement of paper tubes with a stronger material such as a polymeric material or aluminum is not an obvious solution. First, polymeric materials alone will not withstand even conventional winding speeds, because of their tendency to develop "creep" and/or tend to expand at such speeds. Secondly, the proper configuration of the transfer groove cannot be molded or machined satisfactorily in the wall of a polymeric or metallic tube. Even if the proper groove configuration could be molded, merely a change of material does not solve the problems created by the necessity to clean the starting bunch groove. It is still not easy to vacuum the fibers from the groove, and utilizing a knife will still damage the surface of the tube so that it cannot be reused.
Some attempts have been made to strengthen the material from which yarn carriers are made. For example, U.S. Pat. No 4,401,283 discloses an injected molded thermoplastic polymeric winding tube reinforced with glass fibers for use on Leesona 929 type winders. See also U.S. Pat. No. 2,945,638 and West German Patent No. 2,039,517. None of these constructions, however, are believed able to withstand winding speeds of 10,000-12,000 mpm, and none show a starting groove or include any means for cleaning it for reuse.
In each of our copending applications, Ser. No. 200,939 filed May 31, 1988, now U.S. Pat. No. 4,834,314, and Ser. No. 258,l87 filed Oct. 14, 1988, a winding tube is formed in two separable parts, i.e. the main hollow tube portion and a removable end cap. A peripheral groove of some prescribed shape is formed between the confronting end walls of the end cap and hollow tube to receive the transfer bunch during the automatic winding operation. After the yarn package is emptied the end cap is removed or partially removed from the hollow tube portion, the remaining fibers or filaments vacuumed or stripped away, and the end cap replaced. The yarn carrier is then ready for reuse. A French Patent No. 2,463,088 to Viscosuisse, S. A. shows a somewhat related concept in which a paper tube has a friction fit (apparently plastic) slip-on ring releasably attached to the end thereof. The slip-on ring has resilient fingers that fit inside the paper tube and hold the two components in assembled relation.
While the separable yarn carriers identified hereinabove have desirable characteristics and suggest improvements that might lead to a solution of the groove cleaning problem, they do not address the problem of operating at speeds in the range of 10,000-12,000 mpm. The solution to such a problem is not simply to use a heavier material to achieve strength or a lighter stronger material having thinner walls. The heavier weight material will be detrimental to higher speeds, and may also still expand and burst at such high speeds. While there are stronger, lighter weight materials available, they are prohibitively expensive if produced in tubes of a wall thickness of sufficient magnitude to accomodate a starting groove (approximately 0.100 inch). The answer then appears to lie in a separable yarn carrier in which the hollow tube portion is formed of a shell of relatively light, strong material capable of withstanding winding speeds in the range of 10,000-12,000 mpm, yet includes one or more inserts configured so as to fit existing equipment and receive releasable end caps.
In the broadest aspect of the present invention, there is provided a hollow tube and separable end cap forming a starting groove therebetween. The hollow tube is formed of a thin shell of a material having a sufficiently high tensile strength to withstand loads imposed by spinning speeds in the range of 10,000-12,000 mpm and above and one or more inserts which make the thin-walled tube compatible with conventional winding equipment. The end cap may be formed of metallic or suitable polymeric materials, without reinforcement, as the forces exerted thereon are not as great because they may, at least in part, be transferred to the shell.
In its more specific aspects the reusable winding carrier of the present invention includes a hollow tube having an outer, substantially cylindrical surface adapted to carry a filamentary or fibrous yarn thereon. The end cap includes an outer substantially cylindrical surface having generally the same diameter as the outer surface of the hollow tube. The thin shell is formed of a material such as steel, aluminum, metallic alloys, or fiber reinforced polymeric materials selected from the group containing epoxides, polyesters, and vinylesters. When polymeric materials are selected, they must be reinforced by fibers of glass, carbon, ceramics, aramids, or hybrids thereof. The hollow cylindrical shell is provided with an outside diameter substantially equal to the corresponding diameter of paper tubes, but a wall thickness of 0.062 to 0.200 inches (preferably 0.080 to 0.120 inches). The insert is secured to the inner surface of the shell adjacent the end portion and includes an inner wall having an effective diameter substantially equal to the inner diameter of conventional paper tubes. A portion of the thickness of the insert is reduced and provided with internal threads which receive the externally threaded end cap. It is possible that both ends of the hollow tube may include releasable end caps of the type described to further increase the life expectancy of the winding tube by making either end the start-up end. Alternatively, a reinforcing insert might be emplaced on the end of the shell opposite the end cap 20 which may not be threaded, but which absorbs the wear generated by the winding equipment.
A starting or latching groove encircling or partially encircling the yarn carrier is formed between the confronting walls of the hollow tube and end cap. Is some embodiments, the starting groove is formed with a relatively narrow locking portion extending around a portion preferably (approximately 90.degree.) of the groove and a relatively wider lead-in portion extending around the remaining portion of the groove. The lead-in portion guides the first few turns of the transfer tail into the locking portion. The wider and narrower portions of the starting groove are formed by molding recesses into or chamfering one or both abutting ends of the hollow tube and/or end cap during the fabrication of the components. It should be recognized, however, that starting grooves of different shapes can be formed between the end cap and ring in accordance with the present invention. In some winding operations for finer denier yarns, the starting groove may be of a constant size and shape around the entire periphery.
It is therefore an object of the present invention to provide a reusable yarn carrier which is capable of withstanding winding speeds of at least 10,000 mpm.
It is another object of the present invention to provide a yarn carrier of the type described in which an end cap is releasably attached to the main body portion and forms a starting groove therebetween.
It is another object of the present invention to provide a yarn carrier of the type described in which the hollow tube portion is formed primarily of a steel, aluminum, or fiber filled polymeric material.